"Expectations are really going up quickly" in Geneva, Switzerland, that negotiators could announce Friday that they've reached a "first-step agreement that contains the first real limits on Iran's nuclear program in nearly a decade," NPR's Peter Kenyon reports on Morning Edition.

U.S. Secretary of State John Kerry is joining the diplomats in Geneva — adding a stop at the talks to his itinerary for a trip he's been on — and France's foreign minister also may drop in, Peter reports. Their presence has ramped up speculation about an agreement.

The so-called P5+1 talks with Iran are aimed at preventing that nation from developing or obtaining nuclear weapons. Iran says its nuclear program is intended for peaceful purposes. The U.S. and others in the P5+1 (China, France, Germany, Russia and the U.K.) are at the negotiating table because of concern that Iran also is pursuing weapons.

Israel, too, has long insisted that Iran is trying to join the club of nations with nuclear weapons. On Friday, Israeli Prime Minister Benjamin Netanyahu warned that while Iran is getting "the deal of the century ... the international community got a bad deal, this is a very bad deal. Israel utterly rejects it."

What might be in a "first step" deal? Iran is anxious to get out from under crippling economic sanctions. "If Iran agrees to suspend" efforts to enrich uranium, Peter says, "and reduce its existing stockpile ... that would ease a lot of the fears that Tehran is getting closer and closer to someday producing nuclear weapons fuel."

A deal also might include a cap on the number of centrifuges Iran has. They're used to do the enrichment.

In return, Iran might get limited sanctions relief and some badly needed currency.

If negotiators do announce some sort of agreement, "time would be bought to work out a comprehensive nuclear deal over the next coming months," Peter adds.